In daily life, various kinds of monitoring instruments are widely used, such as thermometers for measuring temperature, speedometers used in cars, or the like. However, in some cases, for example, the meter is not precise enough, the monitoring range is too small, or the operation is not convenient etc., it is necessary to install another meter to measure the desired data. In the above situations, a case that there is error between the represented data and the actual data, or the user cannot determine the represented data will be inevitably happened. Such a situation happens because the driving circuits or controlling programs of the monitoring meter are incompatible with the monitored instruments, or encryption has been made to the signal source of the instrument so that the meter cannot read the signal, causing the monitoring instrument to falsely determinate or unable to determine. Hereinafter, only a speedometer is used for illustration.
For a speedometer made from the original factory, the range of the speed per hour is 0˜180 km/h, and the range of the revolution meter is 0˜8000 rpm. When a user needs to additionally install a speedometer whose range of the speed is 0˜220 km/h or a revolution meter whose range is 0˜9000 rpm, he will find that there is error between the results of this new revolution meter and those of the original revolution meter. Therefore, when the detecting programs or driving signals of a monitoring instrument are designed based on general criteria, such instrument can only be used in some kinds of cars. If such instrument is used in the cars designed by different criteria, false determination or inefficient determination can be happened.
Further, there are two categories of cores used in the electronic meters, i.e. air core and stepper motor. These cores can be driven by some controlling programs or transistors associated with driving circuits. However, there are so many kinds of meters that each kind of meter needs a different component and associated driving circuit. As a result, the manufactures or the sellers have to store up a lot of components or products. Also, many components will prolong the manufacturing period.
Further, in the existing meters, signals are transmitted from the sensors to a control box, and compiled and transferred to the meter by encoding and packing the data. The meter is provided with a data processing IC and a signal transferring port therein, such that the data can be transferred to the meter by way of series connecting. The packed data is decoded by the individual meter, and the meter can be operated according to exclusive encoding. However, in practice, such operation has great drawbacks. That is, the meter cannot operate without a control box. In other words, the user should additionally buy a control box so as to operate the meter, resulting in a burden to the consumer.
The existing ways of illumination in meters can be categorized into “back light type” and “side light type”. Besides, there are so many kinds of light sources, such as Tungsten Bulb, Cold Cathode Fluorescent Light (CCFL), Electro-luminescent Light, Light Emitting Diode (LED), etc., no matter which way of illumination and material are used, the main object is to achieve a clear and uniform illumination. However, when illuminating, since the above light sources in the meter panel can only create lighting spots at certain points, the whole meter panel cannot be uniformly illuminated. Further, in the existing meters, an annular meter ring is often provided to press against the meter panel. Such meter ring only serves to press the meter panel without the other functions.
Further, in conventional monitoring meters, each kind of meter is produced for only one purpose. There is no monitoring meter having multiple purposes. Thus, the manufacturer should provide various kinds of methods for manufacturing all meters, such that each kind of meters having required purpose can be manufactured in a mass scale. Although each method can perform the mass production, the manufacture has to store up many components to fit various kinds of meters, resulting in high cost. Therefore, in practice, conventional meters cannot satisfy the above requirements.